Engine starting device



Dec 12, 1950 1.. D. BOYCE 2,533,551

ENGINE STARTING DEVICE Filed May 9, 1947 2 Sheets-Sheet l INVENTOR LEONARD D. BOYCE ATTORNEY Dec. 12, 1950 L. D. BOYCE 2,533,551

ENGINE STARTING DEVICE Filed May 9,1947 2 Sheets-Sheet 2 l INVENTOR LEONARD D. BOYCE ATTORNEY Patented Dec. 12, 1950 ENGINE STARTING DEVICE Leonard D. Boyce, Kirkwood, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application May 9, 1947, Serial No. 747,029

16 Claims.

This invention relates to carburetors for internal combustion engines of the automotive type and consists particularly in a novel automatic control for the choke and throttle valves thereof.

The present generally used type of automatic choke control for automotive carburetors utilizes a bi-metal coiled spring which expands when the temperature is low to urge the unbalanced but, terfly choke valve closed. Because of the restricting action of the choke valve during the warm-up period, the quantity of mixture and, consequently, the power which can be developed by the engine is limited. In fact, maximum torque during this period is developed when the throttle is one-half opened and if the throttle is opened beyond this position, the engine may stall because of the sharp drop in torque and also because of the drop in engine suction which permits the choke valve to close excessively.

Since the thermostat in the present type of automatic choke control is mounted on the carburetor air horn at a point remote from the engine and, particularly the intake manifold thereof, there is a tendency for the thermostat to cool quicker than the engine. Thus, if the engine is stopped before it is fully heated and an attempt is made to restart it within a few minutes, more closing force may be applied to the choke than is desirable to obtain the proper mixture corresponding with the existing engine temperature. Accordingly, the mixture would be too rich and restarting impeded.

It is an object of the present invention'to provide means in an automotive carburetor for preventing excessive opening movement of the throttle during the warm-up period when the choke valve is only partly opened.

Another object is to provide means for preventing excessive opening of the throttle during the warm-up period which means becomes ineffective when the choke valve is in proximity to its fully closed position so as to permit normal functioning of the usual unloader device by means of which the choke can be forced partly opened during cranking upon full opening of the throttle valve.

Another object is to provide means for preventing excessive opening movement of the throttle when the choke valve is only partly opened, which means becomes ineffective when the choke valve is fully opened.

Another object is to provide means for counteracting the portion of the thermostat action which, at low temperatures, effects the final closing movement of the choke valve.

Another object is to avoid the premature closing of the choke valve due to excessive cooling of the thermostat, as explained above.

These objects and other more detailed objects hereafter appearing are attained by the device illustrated in the accompanying drawings in which Fig. 1 is a vertical transverse central section through a carburetor embodying the invention and is taken approximately on line ll of Fig. 4.

Fig. 2 is a side view and section illustrating the right hand side of the carburetor in Fig. 1.

Fig. 3 is a part-al side view and section of the carburetor, as in Fig. 2, but with a part of the automatic choke control mechanism removed for better view of the underlying structure.

Figs. 4 and 5 are views similar to Fig. 3 but showing the parts in different positions.

Fig. 6 is an enlarged view of the throttle limiting detail.

Fig. 7 is a side view of the detail in Fig. 6.

Fig. 8 is an enlarged, somewhat diagrammatic view showing parts which affect opening. movement of the throttle valve.

The carburetor shown is of the downdraft type including a mixture conduit Ill having an air horn II at its upper end controlled by an unbalanced, butterfly choke valve I2 mounted on a shaft l3 and carrying a small spring closed poppet valve 14. A throttle valve 15 is mounted in the lower portion of the conduit on a shaft l6 which has an arm ll rigid with the right-hand extremity thereof for connection to the usual accelerator pedal. The lower extremity of the conduit is flanged, as at I8, for attachment to the engine intake manifold (not shown).

A fuel bowl 20 is formed on the central portion of the carburetor body and receives a float 2| which acts through needle valve 22 in fuel inlet coupling 23 to maintain fuel in the bowl at a substantially constant level. A main metering orifice element 24 in the lower part of the bowl connects with main fuel passage 25 provided with air bleed tube 26 and opening into the throat of venturi tube 21 within the mixture conduit through lateral opening ports 28 in jet bar 29. Bleed tube 26 communicates through a cross passage 30 in the jet bar with air space 3| at the top of the fuel bowl. Passage 30 or space 3| may be connected to the air horn, if desired, or the top of the fuel bowl may be vented directly to atmosphere.

A housing 34 mounted or formed on air horn l I has a removable cover 35 provided with a central pintle 36 which anchors the inner extremity of a thermostatic coil spring 31. A fitting 38 also mounted in cover 35 provides for connection of the interior of housing 34 with a suitable source of heat. such as a stove mounted, as usual, on or within the intake manifold. Choke shaft l3 extends into housing 34 and rigidly mounts therein an arm 40 and a cam element 4|. Formed on one side of housing 34 is an angularly disposed casing 42 for a solenoid 43 which may be connected through a terminal 44 with a suitable source of electric current, such as the usual self starter circuit (not shown). The other side of the solenoid is grounded. Arm 40 has a downward extension 45 with an oil-set plate 45a which forms an armature for solenoid 43 such that when the solenoid is energized and armature 45a is sumciently close to the end thereof, the choke valve will be locked in closed position.

Overlying arm 40 and cam 4| within housing 34 is a plate 46 having a curved slot 41. Arm 40 has an upwardly and outwardly extending finger 48 which projects through this slot. Thermostat 31 (Fig. 2) has its outer extremity hooked, as at 49 so as to engage finger 48 when the thermostat expands under low temperatures, to urge the choke valve closed. As the temperature rises, the thermostat winds upon itself which causes hooked extremity 49 thereof to move away from finger 48 permitting the choke to open by its own weight and suction thereupon.

Pivoted within housing 34 at one side thereof is a lever 50 (Fig. 3) having a finger and inwardly projecting lugs 52 and 53. Lever 50 is operated from the throttle valve by an adjustable link 55 connected at its lower extremity to lobe 56 on lever I1 and at its upper end to a member 51 which slides within a closely fitting guide 58 in the lower wall of housing 34. The portion of member 51 within housing 34 is cut away, as at 53, to form opposing shoulders 60 and 5|. Inward lug 53 on lever it lies between these shoulders so that when the throttle valve is substantially fully opened, upper shoulder-6| bears downwardly on lug 53 to urge lever 50 counterclockwise causing finger 5| thereon to engage a lug 62 on cam 4| to force the choke valve to a partially opened, unloading position. When the throttle is closed, lower shoulder 60 on member 51 engages lug 53 to urge lever 50 clockwise. If

the choke valve is closed at such time (Fig. 3), a

Also secured to pintle 36 on thermostat housing cover is a small coiled spring 13 which has a hooked or outwardly offset extremity 14 which lies in the path of hooked end 48 of the thermostat. A small eye 15 overlies the hooked extremity of spring 13 and maintains this spring in prestressed condition and in position to be engaged by hook 48 on the thermostat during the portion of its action which efiects the last ten degrees only of the choke closing movement. Thus, spring 13 opposes this portion only of the thermostatic action. Preferably, the strength of spring 13 and the thermostat are adjusted so that the thermostat will fully close the choke valve against spring 13 when the temperature is from ten to twenty degrees lower than that at which the choke would be closed if spring 13 were omitted.

In operation, during starting of a cold engine and, conveniently, in response to energizing of the starter circuit, armature 45 will be held by solenoid 43 to aid thermostat 31 in holding the choke valve tightly closed. In case an excessive quantity of fuel is discharged into the intake manifold, this may be unloaded or swept out, in the usual manner, by full opening of the throttle which partially opens the choke valve,

as described above, and subsequent cranking of the engine. When the engine starts to run under its own power, poppet M will promptly open to admit extra air and armature 45a will be released as the starter circuit is de-energized. Thereupon, air flow into the carburetor will cause unbalanced choke valve |2 to open against the resistance of the thermostat and gradually' as the engine becomes fully heated, the thermostat will wind upon itself to permit full opening of the choke valve for normal operation of the carburetor.

When the choke valve is fully closed, high point 1| on cam portion 10 will be at position A (Fig. 8) which permits torsion spring 69 to move stop element 65 and lug 61 counterclockwise against a low point on portion 10 so as to clear upper shoulder 6| on throttle linkage 51. The throttle, then, can be 'fully opened without interference to effect the unloading action. After the choke has been opened approximately 15 degrees, high point 1| will urge lug 61 into the path of shoulder 5| so as to positively prevent downward movement of this shoulder and linkage 51 more than enough to open the throttle valve half way, as shown in Fig. 4. As the choke eccentric pivotal mounting 66 at its upper end' and an ofiset lug 61 at its lower end. A metal strip 68 which may be of fairly stifl spring material, projects downwardly from the top portion of element at one side of lug 61 and into juxtaposition with cam 4|. A small torsion spring 83 constantly urges element 55 in the counterclockwise direction with strip 68 bearing against an individually shaped outer portion 10 on or rigidly secured to cam 4|. Portion 10 has a restricted high point 1| for engaging stri 68 to rock element 65 and bring lug 61 in the path of shoulder 6| on member 51 for a purpose to be described hereafter.

valve approaches to within ten or fifteen degrees of its full opened position, high point 1| again rides oil the bent portion of strip 68, to the position B of Fig. 8. permitting lug 61 to again clear shoulder 6|. Thus, in partly open, intermediate positions of the choke valve, the throttle valve will be limited to one-half opening movement, but when the choke is fully opened or fully closed the throttle is free to open to its full extent. This assures that the throttle cannot be opened far enough to cause the engine to stall during the warm-up period as, whenever the engine is running under its own power, the choke will be opened at least far enough to cause high point 1| on cam portion 10 to lie in the path,

of shoulder 6| on the throttle linkage. Lug .51, of course, again clears the throttle linkage when the choke is in its full open normal running position.

In case the engine is stopped before the engine is fully heated and when the outside temperature is very low, the thermostat may cool faster than the engine. To prevent the excessive expansion of the thermostat and, consequent closing of the choke valve, spring 13 counteracts the portion of the thermostatic action which causes the last -30 degrees of choke closing movement. Eye 15 insures proper prestressing of this spring which, thus, effects only a relatively small portion of the thermostatic action and exerts no force whatever upon the choke valve itself.

Accordingly, the novel choke control solves some of the problems which have vexed users of previous types of automatic choke controls. Various features of the carburetor and choke control are not assential to the invention and these as well as other details may be modified as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claims is contemplated.

I claim: 1. In a carburetor, a mixture conduit having choke and throttle valves therein, a member movable with said throttle valve, said member being formed with a projecting shoulder, a spring actuated arm adapted to move into the path of said shoulder and thereby limit movement of said member, and a cam element actuable responsive to movement of said choke valve to a partly opened position, said cam element adapted to hold said spring actuated arm in the path of said shoulder to interfere with said member and thereby resist opening movement of said throttle valve beyond a predetermined position, said element also being actuable responsive to movement of said choke valve as it approaches its closed position to permit said spring actuated arm to clear said shoulder and thereby avoid interference with the movement of said throttle valve.

2. In a carburetor, a mixture conduit having choke and throttle valves therein,amember movable with said throttle valve, said member being formed with a, projecting shoulder, a spring actuated arm adapted to move into the path of said shoulder and thereby limit movement of said member, and a cam element actuable responsive to movement of said choke valve to a partly opened position, said cam element adapted to hold said spring actuated arm in the path of said shoulder to interfere with said member and thereby prevent opening of said throttle valve beyond a predetermined position, said element also being responsive to opening movement of said choke valve in proximity to its fully opened position to permit said spring actuated arm to clear said shoulder.

3. In a carburetor, a mixture conduit having choke and throttle valves therein, a member movable with said throttle valve, said member being formed with a projecting shoulder, a spring actuated arm adapted to move into the path of said shoulder and thereby limit movement of said member, and a cam element actuable responsive to movement of said choke valve to a partly opened position, said cam element adapted to hold said spring actuated arm in the path of said shoulder to interfere with said member and thereby prevent opening of said throttle valve beyond a predetermined position, said element also being responsive to movement of said choke valve to within ten degrees of its closed position to permit said spring actuated arm to clear said shoulder and thereby avoid interference with throttle opening movement.

4. In a carburetor, a mixture conduit having choke and throttle valves therein, a member movable with said throttle valve, said member being formed with a projecting shoulder, a spring actuated arm adapted to move into the path of said shoulder and thereby limit movement of said member, and a cam element actuable by said choke valve when moved to a partly opened position, said cam element adapted to hold said spring actuated arm in the path of said shoulder to interfere with said member and thereby prevent opening of said throttle beyond a predetermined position, said element also being responsive to movement of said choke valve to within ten degrees of its fully opened position to permit said spring actuated arm to clear said shoulder and thereby avoid interference with opening movement of said throttle valve.

5. In a carburetor, a mixture conduit having choke and throttle valves therein, a member movable with said throttle valve, said member being formed with a projecting shoulder, a spring actuated arm adapted to move into the path of said shoulder and thereby limit movement of said member, and a cam element actuable responsive to movement of said choke valve to a partly opened position, said cam element adapted to hold said spring actuated arm in the path of said shoulder to interfere with the movement of said member and thereby prevent opening of said throttle valve beyond a predetermined position, said element also being responsive to movement of said choke valve in proximity to its fully closed or fully opened positions to permit said spring actuated arm to clear said shoulder and thereby avoid interference with throttle opening movement.

6. In a carburetor, a mixture conduit having choke and throttle valves therein, a member movable with said throttle valve, said member being formed with a projecting shoulder, a spring actuated arm adapted to move into the path of said shoulder and thereby limit movement of said member, and a cam element actuable responsive to movement of said choke valve to a partly opened position, said cam element adapted to hold said spring actuated arm in the path of said shoulder to interfere with the movement of said member and thereby prevent more than one-half opening movement of said throttle valve, said element also being responsive to movement of said choke valve as it approaches its fully open and fully closed positions to permit said spring actuatedarm to clear said shoulder and thereby avoid interference with throttle opening movement.

7. In a carburetor, a mixture conduit having choke and throttle valves therein, a member movable with said throttle valve, said member being formed with a projecting shoulder, a cam rotatable with said choke valve, and a stop element normally in engagement with said cam, said cam having a high point shaped to urge said stop element into the path of said shoulder so as to interfere with the movement of said member when said choke valve has been moved to a predetermined position and thereby prevent full opening movement of said throttle valve.

8. A carburetor as described in claim '7 in which said cam is shaped to move said element to its interfering position relative to said member when said choke valve is moved to a partly opened position.

9. A carburetor as described in claim 8 in which said stop element is normally positioned to clear said member.

10. In a carburetor, a mixture conduit having choke and throttle valves therein, a member movable with said throttle valve, said member being formed with a projecting shoulder, a stop element pivotally mounted adjacent said member, a cam rotatable with said choke valve and located adjacent said stop element, said cam having a high point positioned when said choke valve is in a partly opened position to urge said stop element into the path of said projecting shoulder so as to interfere with movement of said member and thereby prevent opening of said throttle beyond a predetermined position.

11. A carburetor as described in claim 10 in which said stop element is eccentrically pivoted and normally rests in a position to clear said member and thereby avoid interference with throttle opening movement.

12. In a carburetor, a mixture conduit having choke and throttle valves therein, a thermostatic control for said choke valve, an operative connection between said valves for causing opening movement of said choke valve responsive to substantially full opening movement of said throttle valve, a member movable with said throttle valve, said member being formed with a projecting shoulder, a spring actuated arm adapted to block the path of said} shoulder and thereby prevent movement of said member, and a cam element actuable responsive to partial opening 01 said choke valve, said cam element adapted to hold said spring actuated arm in the path of said shoulder to interfere with the movement of said member and thereby prevent opening of said throttle beyond a predetermined position, said element also being actuable responsive to opening to a second position to clear said member responsive to closing movement of said choke valve from said partially opened position thereof.

15. In a carburetor, a mixture conduit having a throttle valve and a suction responsive choke valve therein, a thermostat for urging said choke valve toward its closed position when the temmovement of said choke valve in proximity with its closed position to permit said spring actuated arm to clear said shoulder and avoid interference with throttle opening movement.

13. In a carburetor, a mixture conduit having choke and throttle valves therein, a thermostat for urging said choke valve closed when the temperature is low, an operative connection between said valves for partially opening said choke valve to an unloading position against said thermostat when said throttle valve is fully opened, a member movable with said throttle valve, said member being formed with a projecting shoulder, a spring actuated arm adapted to block the path of said shoulder and thereby prevent movement of said member, and a cam element actuable responsive to partial opening movement of said choke valve, said cam element adapted to hold said spring actuated arm in the path of said shoulder so as l to interfere with said member and thereby preperature is low, a member movable with said throttle valve, and an element movable by said choke valve and adapted, when said choke valve is moved to a partly opened position, to interfere with movement of said member and thereby limit opening movement of said throttle valve, and means normally urging said element to a position to clear said member and thereby avoid interference with throttle opening movement when said choke valve is moved toward its closed position from said partly open position thereof.

16. In a carburetor, a mixture conduit having choke and throttle valves therein, a thermostat for urging said choke valve closed when the temperature is low. a cam device rotatable with said choke valve, a member movable with said throttle valve in proximity to said cam device, a lever forming an operative connection between said member and said cam device including a part for engaging said cam device, responsive to substantially full opening of said throttle valve, to partly open said choke valve against said thermostat, said connection having a second part disposed to engage said cam device when said choke valve is in a restricting position to limit closing movement of said throttle valve to a fast idle position, and a stop element having an operative connection with said choke valve for movement therewith when said choke valve is partly opened to a position to interfere with movement of the member movable with said throttle and thereby prevent full opening movement of said throttle valve, said stop element being movable to a second position responsive to movement of said choke valve toward its closed position from said partly open position to clear said member and thereby permit opening movement of said choke valve by full opening of said throttle valve.

LEONARD D. BOYCE.

REFERENCES CITED The following references are of record in the file of this patent:

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